Composite tablet machine



July 23, 1957 H. M. KERFOOT 2,800,087

COMPOSITE TABLET. MACHINE Y Filed duly 2, 1954 2 Sheets-Sheet 1 l 3. l b 7 B2 I b b 5 b a B a A a o 0 c1 l i I 0) Flsfl Attorney July 1957 r H. M. KERFOOT 2,800,087

COMPOSITE TABLET MACHINE Filed July 2, 1954 g Sheets-Sheet 2 United States Patent COlVIPOSITE TABLET MACHINE Henry Manners Ker-foot, BuirtomEngland Application July 2., 1954, Serial No. 440,943 -4 Claims. (Cl. 107-1) This invention relates to improvements in the formation of compressed tablets such as are employed for medicinal purposes. 1 r

Such tablets are normally formed from a drug in granulated or powder form compressed to the required state and then coated in a rotating pan or the like with a sugar or other palatable syrup from which the moisture is evaporated until the tablet is coated with the required thickness. The coating process is a relatively long operation and the object of the present invention is to speed up the coating process.

According to the invention a layer of coating material in powder or granulated state is introduced to a mould and compressed by a plunger which forms a depression or recess in the material, a predetermined quantity of a drug or drugs is introduced into the depression or recess, and compressed therein and finally a further layer of coating material is applied to the mould and compacted above the drug to produce a tablet having the drug or drugs enclosed by the coating material.

The invention will be described with reference to the accompanying drawings:

Fig. 1 is a diagrammatic front perspective view of a tablet forming machine,

Fig. 2 is an enlarged section of the mould and lower plunger mechanism,

Fig. 3 is a side view of the cam plate for lifting the lower plunger,

Figs. 4 to 15 are sectional views of the top and lower plungers or dies showing the sequence of operations in forming a tablet composed of an outer layer of coating material enclosing the drug or drugs.

The tablet forming machine comprises a lower punch or die a capable of reciprocation in a guide plate A and a plunger a or top punch adapted to move towards the lower punch a to compress material thereon into tablet form.

The machine is driven from a belt pulley A through a worm a and worm wheel a the worm wheel a being mounted on the guide plate A. Coating material is fed from hoppers 1, 3, on to each lower punch or die a as they rotate past the delivering chutes from thehoppers and a drug or drugs in a powder or granulated state is similarly fed from the hopper 2. A stationary cam plate A is mounted below the guide plate A upon which the lower ends of the punches or dies a rest. The cam plate A is formed with two cam rises a and a one of the rises a being greater than the rise a Wheels B, B B are mounted on pillars b on the machine adapted to depress the top plungers or punches a as they pass thereinto. Two of the wheels B, B are formed with a central groove b in their peripheries and the third wheel B is formed with a plain periphery.

The top plunger a is constructed (see Figs. 6, and 14 with a central bore to house 'a rod 0 formed with a collar c engaged by a spring c to normally retain the rod 0 with its lower end flush with the lower end of the plunger 2,800,087 Patented July 23,1957

2 (1 '(Figl 11) but which when the plunger a is engaged by; thewh'e'el B "projects below the end of the plunger a (Fig. 6) to form a recess or depression in the coating material.

In order to produce sugar coated tablets or tablets coated with otherpal'ata'ble coating a layer of coating in granulated or powder state is introduced on to the lower punch a from the hopper 1 (Fig. 3.). The guide plate rotates and the topplungers a are depressed in turn as they travel 'under the plain wheel B and are returned by a spring b or otherwise to their initial position leaving the compressed coating on the lower plunger a (Fig. 7).

The guideplate then passes over 'the cam rise a which raises the plunger a into the position shown in Fig. 8. A drug or drugs is introduced in measured quantity by known means from the hopper 2 into the recess or depression in the coating material (Fig. 9), the plunger a moves off the cam rise a (Fig. 10) and the upper plunger a again depressed by the wheel B (Fig. 11) the rod 0 remaining flush with the lower end of the plunger a as the upper end of the rod (2 travels in the groove b in the wheel B and is not depressed. The upper plunger a rises under the action of the spring b and the compressed coating material and drug remain on the lower plunger a (Fig. 12). Further coating material is applied from the hopper 3 over the material on the lower plunger (Fig. 13) and the upper plunger a is again depressed, by the wheel B to compress the coating material over the drug (Fig. 14). Finally the lower plunger a is raised by the high lift cam rise a to eject the completed tablet onto the guide plate A from which it is re- 1 moved in known manner to a delivery chute.

The production of tablets by the method above described speeds up the production of coated tablets and by suitably dimensioning the upper and lower punches the composite tablet may be of the same size as similar tablets coated by existing methods.

What I claim is:

1. A machine for producing compressed tablets comprising a rotary guide plate supporting upper plungers having spring-loaded rods movable axially thereof and lower plungers, a plain wheel for lowering the upper plungers and their rods, a grooved wheel for lowering the upper plungers independently of their rods, a stationary cam and cam rises thereon for raising the lower plungers to compress coating material between the upper and lower plungers around a centre core of drug, and a stationary frame carrying the rotary guide plate, wheels and cam plate.

2. A machine for producing compressed tablets comprising a rotary guide plate supporting upper plungers, a spring loaded rod passing through a bore in each plunger, a plain wheel to engage each plunger in turn and depress the rods below the lower end of the plunger, lower plungers extending into the rotary guide plate to compress material introduced between the plungers and the rod forming a recess therein, a stationary cam plate over which the lower plungers travel, a cam rise thereon to lift the lower plungers to bring the compressed material to the surface of the guide plate to receive a predetermined charge of drug in the recess, a grooved wheel to depress the upper plungers in turn without relative movement between the plungers and rods to recompress the material and drug, a second grooved wheel to finally repress the material and drug after a further layer of material has been applied, and a second cam rise on the cam plate to raise the lower plungers to eject the compacted tablet on to the guide plate.

3. A machine for producing compressed tablets as defined in claim 2 in combination with three hoppers,

two of which supply the coating material and the third supplying the drug.

4. A machine for producing compressed tablets comprising a rotary guide plate supporting upper plungers, a

spring loaded rod passing through a bore in each plunger, a plain wheel to engage eachplunger in turn and depress the rods below the lower end of the plunger, l-ower plungand drug, and a second grooved wheel to finally repress the material and drug after a further layer of material has ers extending into the rotary guide plate to compress'material introduced between the plungers and therod forming a recess therein, a stationary cam plate over which the lower plungers travel, a cam rise thereon to lift the lower plungers to bring the compressed material to the surface of the guide plate to receive a predetermined charge of drug inthe recess, a'grooved wheel 'to depress the upper plungers in turn without relative movement ,between the plungers and rods to recompres's the material been applied, a second cam rise on the cam plate to raise the lower plungers to eject the compacted tablet on to the guide plate, and a stationary frame carrying the rotary guide plate, wheels and cam plate.

References Cited in'the file of this patent UNITED STATES PATENTS 

